A178526 Triangle read by rows: T(n,k) is the number of nodes of cost k in the Fibonacci tree of order n.

1, 1, 0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 3, 2, 1, 1, 2, 3, 5, 3, 1, 1, 2, 3, 5, 8, 5, 1, 1, 2, 3, 5, 8, 13, 8, 1, 1, 2, 3, 5, 8, 13, 21, 13, 1, 1, 2, 3, 5, 8, 13, 21, 34, 21, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 34, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 55, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 89

Offset

0,9

Comments

A Fibonacci tree of order n (n>=2) is a complete binary tree whose left subtree is the Fibonacci tree of order n-1 and whose right subtree is the Fibonacci tree of order n-2; each of the Fibonacci trees of order 0 and 1 is defined as a single node. In a Fibonacci tree the cost of a left (right) edge is defined to be 1 (2). The cost of a node of a Fibonacci tree is defined to be the sum of the costs of the edges that form the path from the root to this node.

The sum of the entries in row n is A001595(n) = 2F(n+1) - 1, where F(m)=A000045(m) (the Fibonacci numbers).

Sum(k*T(n,k), 0<=k<=n)=A178525(n).

Daniel Forgues, Aug 10 2012: (Start)

The falling diagonals are, starting from the rightmost one, with index 0:

d_0(i) = F(i-1), i >= 0;

d_j(i) = F(i+1), j >= 1, i >= 0.

Equivalently, as a single expression:

d_j(i) = F(i+1-2*0^j), j >= 0, i >= 0. (End)

References

D. E. Knuth, The Art of Computer Programming, Vol. 3, 2nd edition, Addison-Wesley, Reading, MA, 1998, p. 417.

Links

Table of n, a(n) for n=0..90.

Y. Horibe, An entropy view of Fibonacci trees, Fibonacci Quarterly, 20, No. 2, 1982, 168-178.

Formula

T(n,k)=F(k+1) if k<n; T(n,n)=F(n-1); T(n,k)=0 if k>n; here F(m)=A000045(m) (the Fibonacci numbers).

G.f.: (1-tz+tz^2)/[(1-z)(1-tz-t^2*z^2)].

The enumerating polynomials P[n] of row n are given by P[0]=1, P[n]=P[n-1]+F(n-1)*(t^{n-1}+t^n) for n>=1, where F(m)=A000045(m) (the Fibonacci numbers).

Example

In the Fibonacci tree /\ of order 2 we have a node of cost 0 (the root), a node of cost 1 (the left leaf), and a node of cost 2 (the right leaf).
Triangle starts:
1;
1,0;
1,1,1;
1,1,2,1;
1,1,2,3,2;
1,1,2,3,5,3;
1,1,2,3,5,8,5;

Maple

with(combinat): T := proc (n, k) if k < n then fibonacci(k+1) elif k = n then fibonacci(n-1) else 0 end if end proc: for n from 0 to 12 do seq(T(n, k), k = 0 .. n) end do; # yields sequence in triangular form

Crossrefs

Cf. A000045, A001595, A178525.

Sequence in context: A035669 A126863 A106806 * A039958 A029344 A375731

Adjacent sequences: A178523 A178524 A178525 * A178527 A178528 A178529

Keyword

nonn,tabl

Author

Emeric Deutsch, Jun 16 2010

Status

approved